R8B and external power supply
 

A while back I decided to run my R8B off an external power supply. I
can't say my decision to do this was based on any very sound reasoning.
I'd read some old posts in rrr about how keeping heat out of the case
would promote the long term health of the receiver and, being a little
paranoid about protecting my investment, I decided to go with an
external supply (despite the fact that the R8B really doesn't get very
warm when running off its own internal supply). My guess is that that
there's no real need to use an external supply and that my desire to
protect my investment made me a sucker... In any case, I've tried a
couple of external power supplies, most recently a 13.8 VDC / 3amp
supply from Radio Shack, and both of them introduced at least some kind
of noise or hash into my reception. It was often very subtle, but
enough to be a real problem when it comes to weak signals. When the R8B
is running off its own internal supply, it's much quieter. It seems to
like it's own, internal supply.

So my question is, should just I forget about using an external supply?
Thanks in advance!

Steve

wrote:

A while back I decided to run my R8B off an external power supply. I
can't say my decision to do this was based on any very sound reasoning.
I'd read some old posts in rrr about how keeping heat out of the case
would promote the long term health of the receiver and, being a little
paranoid about protecting my investment, I decided to go with an
external supply (despite the fact that the R8B really doesn't get very
warm when running off its own internal supply). My guess is that that
there's no real need to use an external supply and that my desire to
protect my investment made me a sucker... In any case, I've tried a
couple of external power supplies, most recently a 13.8 VDC / 3amp
supply from Radio Shack, and both of them introduced at least some kind
of noise or hash into my reception. It was often very subtle, but
enough to be a real problem when it comes to weak signals. When the R8B
is running off its own internal supply, it's much quieter. It seems to
like it's own, internal supply.

So my question is, should just I forget about using an external supply?
Thanks in advance!

I've never run my R8 or R8B off of an external supply (at least here at home). I
do run the R7 off of one due to one earlier occasion of blowing some diodes in
the internal supply, so just for the heck of it I run my current one off of a 12
volt supply.

The R8 and R8B never run very hot.

dxAce
Michigan
USA

http://www.iserv.net/~n8kdv/dxpage.htm

I use an Astron SS-18, which is a switching supply (so it runs fairly cool),
and is not too noisy birdie-wise. I tried a MFJ switching supply first
(birdies all over) and an Astron non-switching supply (quiet but hot).

It keeps the R8B much cooler, and you can stack other stuff on it because
it no longer needs airflow.

I much prefer it on the external supply, but the real reason for getting
it was to run a couple dozen 12v accessories like active antennas and
ANC-4's and DSP's as well, without having a rats' nest of wall warts.

I have the SS-18 in a discarded refrigerator in the basement, far from
portables lying around that might hear its birdies, and the R8B is on
an external antenna so doesn't hear it in any case.

Be sure to inline-fuse the power from an external supply for the cable you're
using, amp-wise. Those things can burn up wire well before they reach
their rated capacity, and most wire won't handle 18 amps. Slo-blo fuses
run very hot, incidentally; use fast-blow fuses.
--
Ron Hardin


On the internet, nobody knows you're a jerk.

wrote

A while back I decided to run my R8B off an external power supply. I
can't say my decision to do this was based on any very sound reasoning.
I'd read some old posts in rrr about how keeping heat out of the case
would promote the long term health of the receiver and, being a little
paranoid about protecting my investment, I decided to go with an
external supply (despite the fact that the R8B really doesn't get very
warm when running off its own internal supply). My guess is that that
there's no real need to use an external supply and that my desire to
protect my investment made me a sucker... In any case, I've tried a
couple of external power supplies, most recently a 13.8 VDC / 3amp
supply from Radio Shack, and both of them introduced at least some kind
of noise or hash into my reception. It was often very subtle, but
enough to be a real problem when it comes to weak signals. When the R8B
is running off its own internal supply, it's much quieter. It seems to
like it's own, internal supply.

So my question is, should just I forget about using an external supply?
Thanks in advance!

Steve

Heat is an enemy of all electronics, and even though the R8B does run cooler
than any other receiver I own, it could improve frequency stability to run
it even cooler from a DC pwr supply.

Btw I also use a RS 3a regulated pwr supply (to run an ATU) and except for
the spike of turning it on/off, have never noticed any hash on receivers
from it.

Jack

Get a piece of cardboard or a piece of thin wood paneling and push a lot
of long thumbtacks into the cardboard or panel and set the panel on top
of your radio(s) tv sets or whatever with the points of the thumbtacks
pointing up.That should keep the cats off.
cuhulin

Jack Painter wrote:

wrote

A while back I decided to run my R8B off an external power supply. I
can't say my decision to do this was based on any very sound reasoning.
I'd read some old posts in rrr about how keeping heat out of the case
would promote the long term health of the receiver and, being a little
paranoid about protecting my investment, I decided to go with an
external supply (despite the fact that the R8B really doesn't get very
warm when running off its own internal supply). My guess is that that
there's no real need to use an external supply and that my desire to
protect my investment made me a sucker... In any case, I've tried a
couple of external power supplies, most recently a 13.8 VDC / 3amp
supply from Radio Shack, and both of them introduced at least some kind
of noise or hash into my reception. It was often very subtle, but
enough to be a real problem when it comes to weak signals. When the R8B
is running off its own internal supply, it's much quieter. It seems to
like it's own, internal supply.

So my question is, should just I forget about using an external supply?
Thanks in advance!

Steve

Heat is an enemy of all electronics, and even though the R8B does run cooler
than any other receiver I own, it could improve frequency stability to run
it even cooler from a DC pwr supply.

Btw I also use a RS 3a regulated pwr supply (to run an ATU) and except for
the spike of turning it on/off, have never noticed any hash on receivers
from it.

I use a garden variety (Radio Shack) 12V power supply. It does make a
significant improvement in lowering the case temperature but it's hard
to say if this will extend the componant life over the long run. I tend
to think it will, so that's why I do it. There is one down side to the
external DC supply though. When the internal supply is used, the clock
is sync'd to the AC 60-HZ frequency which makes it more accurate than
with the DC supply.

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"Mark S. Holden" wrote:

wrote:

A while back I decided to run my R8B off an external power supply. I
can't say my decision to do this was based on any very sound reasoning.
I'd read some old posts in rrr about how keeping heat out of the case
would promote the long term health of the receiver and, being a little
paranoid about protecting my investment, I decided to go with an
external supply (despite the fact that the R8B really doesn't get very
warm when running off its own internal supply). My guess is that that
there's no real need to use an external supply and that my desire to
protect my investment made me a sucker... In any case, I've tried a
couple of external power supplies, most recently a 13.8 VDC / 3amp
supply from Radio Shack, and both of them introduced at least some kind
of noise or hash into my reception. It was often very subtle, but
enough to be a real problem when it comes to weak signals. When the R8B
is running off its own internal supply, it's much quieter. It seems to
like it's own, internal supply.

So my question is, should just I forget about using an external supply?
Thanks in advance!

Steve

My R8 ran "warm" on the built in power supply, and this made the top of the
radio a favorite snoozing spot for our cats. Having a cat snoozing on top makes
it run warmer.

Without the snoozing cats problem, I'd consider an external power supply to be a
belt and suspenders kind of thing. You don't need to do it, but it may prolong
the life of components.

Besides heat, the other problem with cats snoozing on your radios is eventually,
they decide the tuning knob must be a toy since you seem to enjoy turning it.

I've pretty much decided to sell my Applied Communications (Norlin) SR-2150
wideband because one of the cats is afraid of the cooling fan, and another
thinks turning the tuning knob is a game.

There's also the possibility of cat hair getting inside and interfering
with the air circulation.

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starman wrote:
to think it will, so that's why I do it. There is one down side to the
external DC supply though. When the internal supply is used, the clock
is sync'd to the AC 60-HZ frequency which makes it more accurate than
with the DC supply.

Are you sure it's sync'd? My impression was that it worked off DC in either
case.
--
Ron Hardin


On the internet, nobody knows you're a jerk.

Ron Hardin wrote:

starman wrote:
to think it will, so that's why I do it. There is one down side to the
external DC supply though. When the internal supply is used, the clock
is sync'd to the AC 60-HZ frequency which makes it more accurate than
with the DC supply.

Are you sure it's sync'd? My impression was that it worked off DC in either
case.

The clock circuit uses DC for the active componants but there is a
connection through a capacitor to the AC line to a pin on the clock chip
to sync' it.

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Several people have noted that they use the same external supply from
Radio Shack that I tried, and without a noise problem. This makes me
wonder if the problem is with something *other* than the power supply
itself. Is it possible that the copper wires running from the binding
posts of the power supply to the spring clip terminals on the rear
panel of the R8B are the real problem? In other words, could they be
acting as antennas and picking up the noise I hear? If so, then the
problem would persist no matter which external power supply I used.

Steve

Have you walked your property with a portable radio looking for the
noise source?


On 22 Feb 2005 08:51:30 -0800, wrote:

Several people have noted that they use the same external supply from
Radio Shack that I tried, and without a noise problem. This makes me
wonder if the problem is with something *other* than the power supply
itself. Is it possible that the copper wires running from the binding
posts of the power supply to the spring clip terminals on the rear
panel of the R8B are the real problem? In other words, could they be
acting as antennas and picking up the noise I hear? If so, then the
problem would persist no matter which external power supply I used.

Steve

No, but I don't think I need to. The noise is *only* there when I use
the external power supply.

I don't really mind using the Drake's internal power supply, but I
suspect an external supply would cut down, at least a bit, on the
occasional snaps and pops that come through the AC line.

Steve

wrote:

No, but I don't think I need to. The noise is *only* there when I use
the external power supply.

I don't really mind using the Drake's internal power supply, but I
suspect an external supply would cut down, at least a bit, on the
occasional snaps and pops that come through the AC line.

Steve

First, the diodes in your power supply may not have any RF bypass
capacitors across them. These are intended to suppress the switching
transients caused by the diodes, which can make a humming or buzzing
noise in the radio, especially when it's tuned to a strong shortwave
station. Check to see if there are small ceramic caps' across each
diode.
There's also a possibility that the power supply wires are picking up
some interference being radiated by the digital display circuitry of the
R8B. Try installing a .01-mfd ceramic cap' rated at least 25-V, across
the DC power terminals. You could do the same with a cap' from each
terminal to the chassis ground. Hope this helps.

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